Electrical switch



May 20, 1952 A. HOOD ELECTRICAL SWITCH Filed March 30, 1948 v FIG. 5

ANDREW HOOD IN V EN TOR.

Patented May 20, 1952 ELECTRICAL SWITCH Andrew Hood, Arlington, N. J assignor to The Daven Company, Newark, N. J., a corporation of New Jersey Application March 30, 1948, Serial No. 18,002

1 Claim.

This invention relates to electrical switches and more particularly to a single pole double throw switch for use in controlling an auxiliary signalling circuit anywhere an auxiliary circuit is required on a unit of a signalling or communications circuit.

An object of the present invention is to provide a simple, efficient electric current controlling switch which is attached to an attenuator, potentiometer or like unit for controlling an auxiliary circuit, which switch is operated by operation of the knob of the unit to which it is attached, through the medium of an operating cam.

With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing an electrical switch of a preferred form embodying the invention, and the features forming the invention will be specifically pointed out in the claim.

In the drawings:

Figure l is a side elevation of an attenuator showing the improved auxiliary switch attached thereto.

Figure 2 is an end view of an attenuator having parts broken away to show the improved electrical switch.

Figure 3 is an edge elevation of the switch.

Figure 4 is a longitudinal section through the switch.

Figure 5 is a detailed view of the switch arm operating cam.

Referring more particularly to the drawings, I indicates an attenuator, potentiometer or similar electrical instrument such as employed in communication circuits. The instrument I includes an enclosing housing 2 which is cut away at the knob or outer end of the instrument to form a recess 3 into which the improved electrical switch 4 fits.

The body 5 of the switch 4 is provided with slots 6 along its ends which are slightly angled so as to receive therein and snugly fit the edges I of the housing 2 along each side of the cut away portion 3 so as to provide a slidable connection between the switch 4 and the housing. The switch 4 is held firmly in place when the cover plate 8 of the instrument I is attached to the instrument such as by the attaching screws 9.

The switch structure 4 comprises a body I0 formed of a base member II and a cap member l2. The base member II and cap member I2 are molded of a suitable thermo-setting plastic which is an insulation for electrical currents. The cap member I2 is provided with a recess I3 in its inner face which receives a lug I4 thus providing interlocking means on the base I I and cap I2. The ends of the base II and cap I2 are shaped so as to provide the angularly disposed slots 6 which extend along the ends of the body Ill and receive the edges I of the housing 2.

The base II and cap I2 are rigidly connected one to the other by an eyelet rivet I5. The contact arms I6, I1 and I8 of the switch mechanism are formed of suitable electric current conducting metal and each comprises a length I9 which extends transversely through the body I0 and also extends beyond the outer surface of the cap I2 to provide terminals or terminal arms 20 to which electrical wires may be connected. The portions of the metal strips of which the contact arms are formed adjacent to the portions I9 are bent to lie parallel with each other and with the outer surface of the base II. These parallel lengths indicated at 2| of the metal strips are held in spaced and insulated relation to each other by blocks 22 of suitable insulating material and the lone rivet I5 extends through the parallel lengths 2| of the contact arm forming strips and through the insulating blocks 22 so that the single rivet connects the contact arms, insulating blocks, base II and cap l2 into a unitary switch structure.

The contact arms I6, I1, and I8 are bent at acute angles to the parallel portions 2I and, as clearly shown in Fig. 2, are disposed within the housing 2 of the instrument I. The contact arms I6 and H are stationary and the arm I8 is bent in such manner that it will be tensioned so as to normally engage the inner stationary contact arm I'I.

A cam 23 is pivotally mounted on a suitable post 24 and it has a coil spring 25 connected to the cam 23 and to the post 24 for urging the cam inwardly towards the axis of the rotary adjusting shaft 25 of the instrument I. The outer edge 2'! of the cam 23 is inclined, as clearly shown in Figures 2 and 5 of the drawings, and engages the inner side of the movable contact arm I8 while the inner edge of the cam has a hump 24 formed thereon. The instrument I includes the usual detent gear 21 which is connected to and rotated by the shaft 26 and its rotary movement is limited, as is ordinary in instruments of this type by a suitable stop attached to a detent panel (not shown). An actuating pin 28 is carried by and movable with the detent gear 21. During rotation of the detent gear 21 the pin 28 contacts the hump 24 of the cam 23 and moves the cam 23 outwardly which moves the movable contact arm [8 out of its contact with the inner stationary arm 11, and with the arm l8 at its mid point position the electrical circuit is open. Upon further rotation of the detent gear 27 the cam, due to its'contour continues to move outwardly and the contact arm 18 is moved into contact with the stationary arm l6 thus closing an electrical circuit through the contact arms l8 and i6. At this point the detent gear has reached its limit of forward travel where it is held against further forward movement by the panel carried stop (not shown). When the detent 21 is rotated sufliciently to move the stop pin out of engagement with the hump 24 the spring 25 will move the cam 23 inwardly on its pivot thus allowing detention of the movable contact arm [8 to move it into engagement with the stationary inner contact arm 11.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown, but that they may be widely modified within the invention defined by the claim.

What is claimed is:

A single pole double-throw electric switch comprising a body formed of a base member and a cap member of electrical current insulating material, said cap member provided with a recess in its inner face, a lug on said base member fitting into said recess, a single rivet extending through said cap member and base member at a point remote from said recess and lug to connect said base and cap member rigidly, said base and cap member provided with transversely extending openings therein, strips of electrical current conducting material extending through said openings and beyond the outer surface of said cap section to form connection terminals, said strips 5 of conducting metal being bent to provide parallel extending sections extending substantially parallel to the outer surface of the base section, insulating washers between said parallel sections to hold them in spaced relation, said rivet ex- 10 tending through said washers and parallel sec- 1 .5 ANDREW HOOD.

REFERENCES CITED The following references are of record in the file of this patent:

20 UNITED STATES PATENTS Number Name Date 1,280,566 Sherry Oct. 1, 1918 1,679,503 Siegrist Aug. 7, 1928 5 1,830,138 Smith Nov. 3, 1931 1,913,735 Thompson June 13, 1933 2,025,645 Carpenter Dec. 24, 1935 2,123,052 Kearsley July 5, 1938 2,165,200 Batcheller July 11, 1939 39 2,272,164 Neil Feb. 3, 1942 2,390,846 Obszarny Dec. 11, 1945 2,433,920 Mossman Jan. 6, 1948 2,505,218 Smith Apr. 25, 1950 FOREIGN PATENTS 5 Number Country Date 406,113 Great Britain Feb. 22, 1934 

